Certain prior art schemes measure positional behavior of a rotating member to determine engine performance. Performance metrics often include a measure of combustion performance. This performance may include knock determination compression performance, and misfire detection.
A certain problem with these prior art schemes is that they are complex in form. Specifically, some prior art approaches measure positional behavior of a rotating member by using a counter system as a front end to a microcontroller Arithemetic Logic Unit (ALU). The counter system responds to a speed signal provided by a Hall-effect sensor sensing alternating spaces and marks on a toothed flywheel driven by the engine. By monitoring an output of the counter system, which is indicative of engine speed, the ALU can perform deterministic procedures to compare relative multi-toothed wheel positional behavior performance within partial combustion cycles, over multiple combustion cycles, and also over adjacent cylinder combustion cycles. These deterministic procedures can provide an indication of engine performance. Since these deterministic procedures-thus method steps are indigenous in the architecture of this prior an approach, and the multi-toothed wheel changes position at a very high speed, the computational overhead for the ALU, and utilization of other microcontroller related resources such as Read Only Memory (ROM), Random Access Memory (RAM), counter structures etc. is substantial. An issued patent entitled "SYSTEM FOR MONITORING AND/OR CONTROLLING MULTIPLE CYLINDER ENGINE PERFORMANCE", authored by Deutsch et al. on Jun. 26, 1990, Ser. No. 4,936,277 is an example of such a structure. Often the microcontroller is burdened with other tasks, but because of the resource intensive nature of this prior an approach, larger more complex architectures must be provided. This not only requires more components and potentially higher performance ALU's etc. but also adds to system complexity and cost.
Other prior an schemes have recognized this problem and have tried to reduce further the amount of processing required by the microprocessor by selectively gating period information to the microprocessor. A Simplified Flywheel Speed Fluctuation Monitoring and Control; authorde by Robert W. Deutsch; published in the Motorola, Inc. Technical Developments Volume Apr. 12, 1991 is an example of this. However, this period information still requires significant processing power to convert to acceleration information and to obtain performance information.
Still other prior art schemes use digital signal processing of the positional behavior of a rotating member to determine engine performance. These systems are also very complex and resource intensive. Typically, the positional behavior of the multi-toothed wheel is convened from its analog form to a digital representation and then digital signal processing method steps are executed to determine engine performance. Again, this approach is very costly, complex, and resource intensive.
What is needed is an improved system and method for measuring reciprocating engine performance dependent on positional behavior of a rotating member driven by the engine, that is less complex, requires less ALU computational overhead, and is less costly.